Metal-containing fuel additives are known in many forms, from homogeneous solutions in aqueous or hydrocarbon carrier media, or heterogeneous particle clusters extending all the way to visible particles formulated in the slurry form. In between is the nanoparticle range commonly defined to be metal particles above cluster size but below 100 nanometer size range. In all known instances where these metal-containing additives are used, they are introduced to the fuel/combustion/flue gas systems as single, metal-containing additive formulations or as mixtures of different metals.
Metal-containing fuel additives of the nature described above are usually formulated as water soluble or oil soluble concentrates, either as homogeneously dissolved metals or metal nanoparticles. In a lot of instances, the concentrates are micelle dispersions in a carrier fluid, or particle suspensions containing the desired metal atoms. In cases where more than one metal is deemed necessary, then simple mixtures of the desired metals are included either in the same formulation, or added to the fuel separately.
The current use of metals in combustion systems relies on chemistries fostered by each metal type as dictated by its unique orbital and electronic configuration described apart. This means that in additives formulated with metal mixtures, at the time of the intended activity the metals act independently from one another during fuel combustion. In fact the physics of a combusting charge is such that there is no likelihood that a mixed metal additive will land the different metal atoms within the same location on the combusting fuel species so that they may act in unison as one compound.
The physical form of metal-containing additives of most recent interest is the nanoparticle form because of its unique surface to volume ratios and active site numbers and shapes. As is to be expected, there is interest in mixed metal nanoadditves because each metal tends to have specific functions.
Combustion systems burning hydrocarbonaceous fuels experience various degrees of combustion inefficiencies due to fuel properties, system design, air/fuel ratios, residence time of fuel/air charge in the combustion zone, and fuel/air mixing rates. These factors lead to imperfect combustion giving rise to at least one of 1) a lowering of targeted efficiencies, 2) elevated emission of environmental pollutants, 3) lowered operating durability due to deposits in the combustion system, and 4) corrosion of system hardware due to the presence of undesirable fuel borne corrosion precursors that are converted to corrosives during certain combustion conditions. Fuel-side solutions to these problems usually involved some sort of “clean fuel” selection based upon tested criteria, or simply the use of additives.
What is needed is an additive composition that can be formulated to enhance a specific function and improve at least one of the problems addressed above.